Water heating system



c. M. OSTERHELD WATER HEATING SYSTEM Filed Jan. 50, 1941 v INVENTORCLARK/VOSER/flp BY M2276 ATTORN Y I I II IA 1/ 11/ 1/ I /I II [1 Dec.16, 1941.

Patented Dec. 16, 1941 WATER HEATING SYSTEM Clark M. Osterheld,Stoughton, Wis., assignor to McGraw Electric Company, Elgin, 111., acomration of Delaware Application January 30, 1941, Serial No. 376,580

1 Claim.

My invention relates to electric heating systems and particularly toall-day water heating systems.

An object of my invention is to provide relatively simple meansincluding a timer and a plural-contact plural-position switch controlledby said timing means to cause energization of a single electric heateron a hot water tank to heat different amounts of water in the tank atdifferent times of a twenty-four hour day.

Other objects of my/invention will either be apparent from a descriptionof a system embodying my invention or will be pointed out hereinafter inthe course of such description and set forth in the appended claim.

In the drawing,

Figure l is a view of a system embodying my invention as applied to anordinary domestic hot water tank, the latter being shown in verticalsection, and,

Fig. 2 is a view of 'a part of the continuously operative timing meansshown in a different position than that in which it is shown in Fig. lof the drawing.

I have shown a-domestic hot water tank ll having a cold water inlet/pipel3 and a hot water outlet pipe l5 connected with the tank at the bottomand at the-top thereof. The tank may be provided with a mass ll of heatinsulating material whichma jbe heldin proper operative position by'asuitable outer casing I9. I desire to pointout that 'while'I have showna long cylindrical domestic hot water tank, my invention is not limitedthereto and further that the tank is shownjgenerally only;

I provide a single electric heater 21 mounted on and around the outsideof the lower end portion of the tank and this heater may be mounted in asuitable tunnel 23 as now well known inthe art.

I provide a main thermally-actuable heater 7 control switch 25 includinga bimetal bar 21 maljswi'tch includes a bimetal bar 33 having a 5fixed'support which is subjected to the temperature of an upper part ofthe tank and therefore of. the water in the tank, this switch includingfurther a fixed contact member adapted to be engaged by and bedisengaged from the free end of the flexing bimetal strip 33. I haveshown the main and the auxiliary thermally actuable switch schematicallyonly and desire it to be understood that the details of construction of.these; switches constitute no part of my present invention and that Imay use any other thermally actuable type of switch effective for thesame purpose as those shown in Fig. 1 or the drawing.

I provide further a continuously operative timing means 31 whichincludes a synchronous motor 39 of the kind now used in electric clocks.The terminals of the motor winding are connected by wires 4| and 43 tosupply circuit conductors 45 and 41 respectively whereby a continuouslyoperative timing means is provided. The shaft of motor 39 may havemounted thereon a worm wheel 49 meshing with a worm gear 5| which wormgear is mounted on a shaft 53. While I have not shown any bearings forshaft 53, I desire it to be understood that such bearings or othersupports will be furnished and I desire to point out further that theworm gear 5| is adapted to be driven through one complete revolutionevery twenty-four hours by means equivalent to the worm and the wormgear shown in Fig. 1.

I mount further a disc on shaft 53 and provide a cam slot in the outersurface of said disc 55, this slot having two portions 51 and 59.Portion 51 extends in the shape of a groove of uniform radius in oneface of disc 55, the time extent being substantially sixteen hours andequal to the time length of an on-peak period. The peripheral timeextent of portion 59 of the groove having a larger radius is thereforethat of an off-peak period of substantially eight hours. It is to beunderstood that the disc 55 will be so mounted on the shaft 53 that thstart of an off-peak period of eight hours may be set for say 10 P. M.so that the end of the off-peak period provided by the constantlyoperative timing means will be substantially 6 A. M.

I provide a triple-arm switch 5| including a first outer contact orswitch arm 53, an interv mediate movable switch or contact arm and asecond outer contact arm 61. The outer end of switch arm 65 has mountedthereon a small block 59 of electric insulating material into whichthere projects one end of a bar H having secured thereto at its outerend a pin 13, which is adapted to fit into the cam groove comprising theportions 51 and 59. The position of the outer contact arms 63 and 61 islimited by suitably supported stop pins '15 and I1 to the effect thatwhen pin 13 on bar "H on the intermediate switch arm 55 is in theportion 59 of the groove, contact arms 65 will be in engagement with theouter contact arm 61, as shown in Fig. l of the drawing. On the otherhand, when pin 13 is in Supply circuit conductor 45 is connected by aconductor l9 with intermediate contact arm 65. Contact arm 63 isconnected by a conductor 8| with contact member 35 of the upper orauxiliary thermally-actuable switch 3|. The fixed end of bimetal bar 33is connected by a conductor 83 with the fixed end of the bimetal bar 21of the main or lower thermally-actuable switch 25 and also to oneterminal oi the heater 2|. The other terminal of heater 2| is con nectedby conductor 85 with the other supply circuit conductor 4.1. The fixedcontact member 29 of the lower or main thermally-actuable switch 25-isconnected by a conductor 81 with the other outer contact arm 61.

At the start of an on-peak period, shown in Fig. 2 of the drawing, theinner or intermediate contact arm 65 has been moved into engagement withthe right-hand outer contact arm 63 whereby an energizing circuitthrough the heater 2| is provided substantially as follows: from supplycircuit conductor 45 through conductor 19, contact arms 55 and 63,conductor 8|, contact 35,

bimetal bar 33, conductor 83, resistor 2| and from there throughconductor 85 to the other supply "circuit conductor 61. The bimetal bar33 is shown in the shape it would have it it were subjected to thetemperature of hot water in the upper portion oi the tank H and eventhough the contact arms 63 and 65 were in engagement with each other,the heater would not be energized as long as the free end of bimetal bar33 remained out of engagement with the contact member 35 because thethermostat is subjected to the temperature of hot water. Let it beassumed, however, that hot water is withdrawn from the tank H one orseveral times during the on-peak period as defined by the groove 57,then the hereinbefore described energizing circuit through the heater 2|would be eflected and heating up of the water in the tank would result.This energization of the heater 2! would continue until a predeterminedfractional part of the water contents of the tank had been heated to adesired adjustable relatively high temperature and this amount of waterwould extend to the position occupied bythe upper or auxiliarythermostatic switch 3|. Opening of the upper thermally actuable switch3| would cause deenergization of the heater 2| which would mean that theheater 2| connected to the continuously energized supply circuit andcontrolled by the plural-arm and plural-operative-position time acontrolled switch would be deenergized as long as a certain amount ofhot water is in the'tank.

Should withdrawal of hot water from the tank occur during the day withresultant reclosure of the. upper thermal switch 3|, reenergization ofthe heater 2| would occur and would continue until the predeterminedfractional part of the water content of the tank had again been heatedto a given temperature when deenergization of the heater would occur. Itis thus evident that the system embodying my invention would cause thetank to tend to maintain hot a predetermined amount of water in the tankduring the on-peak period.

At the start of an oii-peak period when the disc 55, turned by the motor39 in the direction indicated by the arrow, hasreached the positionshown in Fig. 1 of the drawing where switch arm will have been movedinto engagement with switch arm 61, any possible energizing circuitthrough the switch arm 63 and the upper thermally actuable switch 3|will be opened and another energizing circuit through the heater will beprovided substantially as follows: from supply circuit conductor 45,through conductor 19, through contact arms 55 and 61, through conductor81 to contact 29, through the en gaging bimetal bar 21, through heater2| and from there through conductor 85 to the other supply circuitconductor 45. This means that at the start of an oil-peak period in casethe tank is not entirely full of hot water, the heater 2| will beenergized through the last described energizing circuit and willtherefore tend to cause heating up of all or the water in the tank.

I desire to point out that the length of offpeak period is determined bythe character of the loads connected to the supply circuit conductors ofthe public service 0r utility company and that the energization of theheater 2| through the last above described circuit including the mainlower thermal switch 25 will be effected substantially at the beginningof an oil-peak period. The energization of the heater through thiscircuit will continue until all of the water in the tank is hot when themain thermal switch 25 will cause deenergization of the heater.

Should withdrawals of hot water occur during the oil-peakperiod aiterthe heater has been deenergized as above described, the heater willagain be energized by the switch 25 and this energization will continueuntil the end of the ofi-peak period in case all of the water in thetank has not been heated to the desired high temperature before the endof the oil-peak period.

The system embodying my invention therefore provides 'a pluralcontactswitch having a plurality of operative positions, moved into aselected one of said operative positions by timecontrolled means, whichmay also indicate the time of day. to tend to maintain a predeterminedamount of hot water in the tank during the daytime or on-peak hours andto ensure the start of an ofl-peak period with a'tank' full of hotwater.

Various modifications may be made in the 'system embodying my inventionwithout departing from the spirit and scope thereof and I thereforedesire that all such modifications as are clearly covered by theappended claim shall be included as a part of my invention.

I claim as my invention:

A water heating system for a hot water ta having a single electricheater on said tank near the bottom end thereof, comprising twothermally-actuable heater control switches responsive to tank watertemperature at diflerent heights of the tank, a continuously operativetimer, a plural-contact switch having two operative'positions andadapted to be moved into one and then the other of said operativepositions at different periods of a twenty-four hour day and electricconnections between the electric heater, the thermally-actuable switchesand the pluralcontact switch to cause energization of the single heaterthrough the upper thermally-actuable heater control" switch during oneof said periods of day and to cause energization of the single heaterthrough the lower thermally-actuable heater control switch during theother of said periods of day and to cause deenergization of said singleheater when the current-carrying thermal switch is subject to hot water.

CLARK M. OSTERHELD.

